Joint structure for refrigerant discharge tubes used in hermetic compressors

ABSTRACT

A joint structure for a refrigerant discharge tube of a hermetic reciprocal compressor having a connecting member fit around the refrigerant discharge tube, the connecting member having a shape corresponding to a connecting hole in a cylinder block, thereby allowing the connecting member to be press-caulked. The refrigerant discharge tube is directly connected to the cylinder block. The connecting hole is multi-layered and may be formed into at least two steps. The connecting member is pre-assembled in the connecting hole by transition-fitting. Accordingly, as the connecting member is press-fit in the connecting hole by a caulking-jig, the connecting member is expanded, and the connecting member is more securely fit in the connecting hole. Further, a thread portion having a pitch in a range of 2 to 5 threads is formed on an inner circumference of the connecting hole. Accordingly, the expanded connecting member penetrates into the thread portion, strengthening the connection between the connecting member and the connecting hole. Since the refrigerant discharge tube is directly connected to the cylinder block, structure is simplified, while the number of assembling steps is reduced. As a result, productivity increases and the manufacturing costs decrease. Further, since the connecting member is fit in the connecting hole by the press-caulking instead of the brazing, higher durability is guaranteed and thus, the breakage of the refrigerant discharge tube is prevented.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention generally relates to a hermetic reciprocalcompressor, and more particularly to a joint structure for a refrigerantdischarge tube that serves as a passageway for compressed refrigerant.

[0003] 2. Description of the Prior Art

[0004] As shown in FIG. 1, a conventional hermetic reciprocal compressorincludes an electronic device unit 20 and a compression device unit 30in a casing 10 which is formed of an upper shell 11 and a lower shell12. The compression device unit 30 is driven by the power transmittedfrom the electronic device unit 20 used to compress the refrigerant.

[0005] The electronic device unit 20 includes in the casing 10 a stator21 which is fixed, a rotor rotatably disposed relative to the stator 21and a rotary shaft 23 press-fit in the rotor 22 and having an eccentricportion 23 a formed at an end thereof.

[0006] The compression device unit 30 includes a cylinder block 31having a compression chamber 31 a, a cylinder head 40 mounted on thecylinder block 31 and having a refrigerant suction chamber 41 and adischarge chamber 42, a piston 50 disposed in the compression chamber 31a of the cylinder block 31 disposed to be movable in a reciprocalfashion, a connecting rod 60, with one end being connected to the piston50 and the other end connected to the eccentric portion 23 a of therotary shaft 23, for converting and transmitting the rotary motion ofthe rotary shaft 23 into the linear reciprocal movement of the piston50, and a valve device 70 disposed between the cylinder block 31 and thecylinder head 40 for controlling the flow of the refrigerant.

[0007] Further, the hermetic reciprocal compressor includes a suctionmuffler 80 at one side of the interior of the casing 10 for drawing inthe refrigerant into the refrigerant suction chamber 41, and arefrigerant discharge tube assembly 90 (FIG. 2) disposed adjacent arefrigerant path hole (not shown) formed in the cylinder block 31 toprovide fluid communication with the refrigerant discharge chamber 42 ofthe cylinder head 40. The refrigerant discharge tube assembly 90 servesas a discharge passageway of the compressed refrigerant.

[0008] As shown in FIG. 2, the refrigerant discharge tube assembly 90includes a refrigerant discharge tube 91 and a discharge muffler 92. Thedischarge muffler 92 defines a predetermined space to reduce the noiseproduced from the pulsation of the refrigerant discharge, and is securedto the cylinder block 31 by a bolt 93. One end of the refrigerantdischarge tube 91 is connected to the discharge muffler 92, while theother end is connected to a discharge tube (not shown) provided in thecasing 10.

[0009] In the refrigerant discharge tube assembly 90 as described above,the refrigerant discharge tube 91 and the discharge muffler 92 arejoined with each other by copper-brazing, and the discharge muffler 92is coupled with the cylinder block 31 using the bolt 93.

[0010] According to the conventional joint structure for the refrigerantdischarge tube, the refrigerant discharge tube 91 and the dischargemuffler 92 are joined [with] to each other by copper-brazing, and thenthe discharge muffler 92 is coupled to the cylinder block 31 by the bolt93. Accordingly, the number of assembly steps increases, causing themanufacturing efficiency to be reduced and manufacturing costs toincrease.

[0011] Also, as the refrigerant discharge tube 91 and the dischargemuffler 92 are joined with each other by copper-brazing, the refrigerantdischarge tube 91 becomes deformed and phase-variation occurs in thestructure in the brazing furnace. As a result, durability of the productdeteriorates. Even after the brazing, the neck portion of therefrigerant discharge tube 91 is subject to stress during one or morebending processes, and thus, the refrigerant discharge tube 91 becomesless cylindrical, and stress concentration occurs. As a result, oftentimes, the refrigerant discharge tube 91 is broken, and the refrigerantleaks out of the compressor.

SUMMARY OF THE INVENTION

[0012] Accordingly, it is an object of the present invention to providea joint structure for a refrigerant discharge tube used in a hermeticreciprocal compressor, which requires fewer operational steps forjoining the refrigerant discharge tube relative to the cylinder block,thereby contributing to the improvement of the manufacturing efficiencyand to a reduction in manufacturing costs.

[0013] It is another object of the present invention to provide a jointstructure for a refrigerant discharge tube used in a hermetic reciprocalcompressor, intended to overcome problems of durability deteriorationand refrigerant discharge tube breakage which may occur due tocopper-brazing, by press-fitting the refrigerant discharge tube to thecylinder block.

[0014] The above objects are accomplished by a joint structure for arefrigerant discharge tube used in a hermetic reciprocal compressoraccording to the present invention, in which the refrigerant dischargetube is directly connected to a cylinder block by press-caulking aconnecting member connected with the refrigerant discharge tube into aconnecting hole formed in the cylinder block. The connecting member isformed to correspond to the shape of the connecting hole.

[0015] The connecting hole is formed in a multi-layer or steppedstructure, which has at least two layers. For assembly, the connectingmember is pre-assembled in the connecting hole by transition-fitting,and then is securely press-fit in the connecting hole by being expandedtherein under the pressure of a caulking jig.

[0016] According to the preferred embodiment of the present invention,the connecting hole has a thread portion having a pitch in the range of2 to 5 threads, and thus, the connecting member is more securely fit inthe connecting hole because the connecting member is expanded by thepressure provided by the caulking jig.

[0017] The connecting member can be formed of a soft iron metal or asoft non-iron metal.

BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The above-mentioned objects and the feature of the presentinvention will be more apparent by describing the preferred embodimentof the present invention in detail referring to the appended drawings,in which:

[0019]FIG. 1 is a cross-sectional view schematically showing thestructure of a conventional hermetic reciprocal compressor;

[0020]FIG. 2 is a perspective detail view showing a joint structure fora refrigerant discharge tube used in the compressor shown in FIG. 1;

[0021]FIG. 3 is a cross-sectional view showing the joint structure for arefrigerant discharge tube used in a hermetic reciprocal compressoraccording to the preferred embodiment of the present invention;

[0022]FIG. 4 is a cross-sectional view showing the refrigerant dischargetube being connected to the cylinder block by the joint structureaccording to the present invention; and

[0023]FIG. 5 is a perspective view showing the hermetic reciprocalcompressor according to the present invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT

[0024] The objects and other characteristics of the present inventionwill be made more apparent by describing the preferred embodiments withreference to the accompanying drawings. Elements that are similarlyconstructed and have similar functions as those like elements of FIGS. 1and 2 will be identified by identical reference numerals in FIGS. 3-5.

[0025] Referring to FIGS. 3 and 4, the joint structure for therefrigerant discharge tube of the hermetic reciprocal compressoraccording to the preferred embodiment of the present invention includesa connecting hole 101 penetrated through a side of the cylinder block100, a refrigerant discharge tube 110 fit in the connecting hole 101 anda connecting member 120 for securing the refrigerant discharge tube 110relative to the connecting hole 101.

[0026] The connecting hole 101 is formed to be in fluid communicationwith a refrigerant path hole (not shown) formed inside of the cylinderblock 100. The refrigerant path hole is in fluid communication with therefrigerant discharge chamber 42 of the cylinder head 40 (see FIG. 1).The connecting hole 101 is formed having a multi-layer structure inwhich two or more layers are formed, and may be provided with a threadportion 101 a formed in an inner circumference of the hole 101 having apitch in a range of from 2 to 5 threads.

[0027] The refrigerant discharge tube 110 is inserted in an insertionhole 120 a formed in the center of the connecting member 120, andaccordingly, the refrigerant discharge tube 110 is connected to thecylinder block 100 as the connecting member 120 is secured to theconnecting hole 101.

[0028] The connecting member 120 is also formed having a multi-layerstructure corresponding to the shape of the connecting hole 101, and isforce-caulked in the connecting hole 101 by a pressing member, such asthe caulking jig 130 shown in FIG. 3.

[0029] Preferably, the connecting member 120 is formed of materialshaving rigidity, but that allow inward or outward expansion by thepressure of the caulking jig 130. Soft iron metal, or soft non-ironmetal, can be used as the connecting member 120.

[0030] Hereinbelow, the method of using the joint structure for therefrigerant discharge tube of the hermetic reciprocal compressoraccording to the preferred embodiment of the present invention will bedescribed.

[0031] First, as shown in FIG. 3, the connecting member 120 is fit inthe refrigerant discharge tube 110, and pre-assembled in the connectinghole 101 of the cylinder block 100 by transition-fitting.

[0032] Next, the connecting member 120 is pressed from the rear side bythe caulking jig 130, press-fitting the connecting member 120 into theconnecting hole 101. At this time, the connecting member 120 expandsinwardly and outwardly, coming into close contact with the refrigerantdischarge tube 110 relative to the refrigerant discharge tube 110inserted in the insertion hole 120 a of the connecting member 120, withthe connecting hole 101 and the connecting member 120 contacting eachother very tightly. Due to the presence of the thread portion 101 a onthe inner circumference of the connecting hole 101, the connectingmember 120 penetrates into the threaded portion 101 a during expansion,thereby being press-fit in the connecting hole 101 tightly.

[0033]FIG. 4 is a view showing the connecting member 120 beingpress-caulked in the connecting hole 101. As shown in FIG. 4, therefrigerant discharge tube 110 is secured in the cylinder block 100 dueto the expansion of connecting member 120 into the connecting hole 101.As described above, the connecting member 120 is secured in theconnecting hole 101 by being expanded under the external pressure of thecaulking jig 130 (FIG. 3), and is further tightly secured due to theconnecting member 120 being partially and fixedly penetrated into thethread portion 101 a formed on the inner circumference of the connectinghole 101. As a result, a strong binding force is acquired, and theconnecting member 120 is not separated from the connecting hole 101.

[0034]FIG. 5 shows the hermetic reciprocal compressor having the jointstructure for a refrigerant discharge tube as described above. As shownin FIG. 5, the refrigerant discharge tube 110 is directly secured to thecylinder block 100 by the connecting member 120.

[0035] As described above, according to the present invention, since therefrigerant discharge tube 110 is directly connected to the cylinderblock 100, the structure becomes simplified, while the number ofassembly steps required for assembling the compressor is reduced. As aresult, manufacturing efficiency improves and manufacturing costs arereduced.

[0036] Further, since the connecting member is secured bypress-caulking, instead of brazing, durability is increased, and thus,breakage of the refrigerant discharge tube 110 can be prevented.

[0037] Although a preferred embodiment of the present invention has beendescribed, it will be understood by those skilled in the art that thepresent invention should not be limited to the described preferredembodiment, but various changes and modifications can be made to remainwithin the spirit and scope of the present invention as defined by theappended claims and their equivalents.

What is claimed is:
 1. A joint structure for a refrigerant dischargetube of a hermetic reciprocal compressor, the refrigerant discharge tubebeing formed on a cylinder block of the hermetic reciprocal compressorand serving as a passageway for a refrigerant being discharged, thejoint structure comprising: a connecting hole formed in the cylinderblock in fluid communication with a refrigerant path hole formed insideof the cylinder block; and a connecting member having a shapecorresponding to the connecting hole providing for insertion into theconnecting hole, whereby the connecting member is directly connectedwith the cylinder block by press-caulking of the connecting member inthe connecting hole.
 2. The joint structure of claim 1, wherein theconnecting hole is formed as a multi-layer structure including two ormore layers, and the connecting member is pre-assembled in theconnecting hole by transition-fitting, whereby the connecting member iscompletely press-fit in the connecting hole by expansion therein underthe pressure of a caulking jig.
 3. The joint structure of claim 2,wherein the connecting hole comprises a thread portion having a pitch ina range of 2 through 5 threads, whereby the connecting member is furthersecured as the connecting member penetrates into the thread portion bybeing expanded under the pressure of the caulking jig.
 4. The jointstructure of claim 2, wherein the connecting member is comprised of asoft iron metal.
 5. The joint structure of claim 2, wherein theconnecting member is comprised of a soft non-iron metal.